Household fuel cells and fuel cells for powering automobiles and the like generate electric power by reacting a hydrogen-containing gas with, for example, oxygen in air. The hydrogen-containing gas is generated in a reformer by using methane gas, propane gas, an alcohol, or the like, as a raw material. The hydrogen-containing gas generated in the reformer contains carbon monoxide, ammonia, etc. Such impurities are known to degrade, for example, electrodes of a fuel cell.
In order to suppress the degradation of electrodes and the like, which is caused by ammonia contained in the hydrogen-containing gas, there is a proposed solid polymer fuel cell system configured to remove ammonia from the hydrogen-containing gas by an ammonia remover which removes ammonia by causing the hydrogen-containing gas and water to come into contact with each other, or by causing moisture in the hydrogen-containing gas to be condensed and dissolving ammonia into the condensation water, thereby reducing the concentration of ammonia in the hydrogen-rich gas to 5 ppm or lower. Thereafter, the solid polymer fuel cell system supplies the hydrogen-rich gas to a solid polymer fuel cell (see Patent Literature 1, for example).
Similarly, there is a proposed reformed gas supply apparatus including an ammonia remover configured to cause a reformed gas obtained in a reformer to come into contact with water, such that ammonia contained in the reformed gas is absorbed into the water, thereby removing ammonia from the reformed gas (see Patent Literature 2, for example).
Meanwhile, there is a fuel cell system in which a passage for flowing a hydrogen-containing gas generated in a reforming device is provided with a hydrogen inlet valve 21, a hydrogen outlet valve 28, and a bypass valve 30. These valves are closed while a power generation operation is stopped, and thereby communication between the passage and the atmosphere is blocked (see Patent Literature 3, for example).